Apparatus for thermal processing with micro-environment

ABSTRACT

A substrate thermal processing system. The system has at least one substrate holding module having a housing configured for holding an isolated environment therein. A substrate heater is located in the housing and has a substrate heating surface. A substrate cooler is located in the housing and having a substrate cooling surface. A gas feed opening into the housing and feeding inert or reducing gas into the housing when the substrate is heated by the heating surface. A gas restrictor is within the housing restricting the fed gas between the substrate heating surface and a surrounding atmospheric region substantially surrounding the substrate heating surface in the housing and forming an aperture through which the fed gas communicates with the atmospheric region.

BACKGROUND

1. Field of the Disclosed Embodiments

The disclosed embodiments relate to semiconductor device fabrication,and more particularly to a method and apparatus for processing ofsemiconductor substrates.

2. Brief Description of Earlier Developments

Integrated circuits are generally built on a silicon wafer base andinclude many components such as transistors, capacitors and otherelectronic devices connected by multiple layers of wiring, orinterconnect. Most advanced chips are now constructed with copperinterconnects, since copper has lower resistivity than aluminum. Theseinterconnects are often multi-level and are formed by fillinghigh-aspect ratio features, such as vias and trenches. These featuresare filled first with dielectric barrier layers followed by metal seedlayers using either physical vapor deposition (PVD) or chemical vapordeposition (CVD). After the seed layer, the interconnect features arefilled with copper using electrochemical plating (ECP). This processsequence is used for front-end-of-line applications such as copperdamascene interconnects and also for the larger interconnects used inadvanced packaging. Alternate process sequences are also underdevelopment to eliminate the need for seed layers and allow directelectro-plating on silicon or on barrier materials.

Copper damascene and direct plating processes use one or more annealsteps to improve interconnect properties and to facilitate furtherprocessing. Anneal is used to increase electrical conductivity via grainrefinement, to reduce via pullout and voids via stress relaxation and toreduce the possibility of failures due to electro-migration. Annealingleaves the copper in a known state, which is necessary for reliabledown-stream processing. For example, having a known, uniform state ofhardness and grain size is required to achieve stable process controlfor chemical-mechanical-polishing (CMP), the most common post-platingprocess step.

Semiconductor annealing can be performed by a variety of equipment.Anneal equipment include ovens, vertical furnaces, rapid thermalprocessing systems and specialized modules. Furnaces and other dedicatedexternal anneal system have the disadvantage that they requireadditional wafer handling, as the wafers are transported to thededicated tool in a specialized carrier. Specialized modules may bedirectly attached to electro-plating tools. Directly attached moduleshave the advantage that anneal can be incorporating directly into theelectro-plating recipe, and wafers can be annealed one or more times asnecessary during plating.

Annealing may be typically done for several minutes at a temperature of200-400° C. Annealing may be performed in an inert or reducing gasatmosphere to prevent oxidation. The most common atmosphere is nitrogen,although forming gas (a mixture of nitrogen and hydrogen) is sometimesused. Wafers are typically brought to the anneal temperature by placingthem close to a heated chuck for a recipe-dependent time. Wafers arethen cooled either by natural convection or by contact with a coolsurface. They are then returned to a cassette or specialized enclosureand transported to the next processing tool.

Anneal chambers for semiconductor processing may be divided into twotypes based on their geometry. Vertical anneal chambers have theirheating area vertically below their cooling area. Horizontal annealchambers have their heating area horizontally adjacent their coolingarea. A representative vertical geometry anneal chamber with a heatingarea below the cooling area is described, for example, in U.S. Pat. No.6,929,774 by Morad et. al. A representative horizontal anneal chamberwith a heating area horizontally adjacent to a cooling area is describedin U.S. Pat. No. 7,311,810 by Mok et al., both of which are incorporatedby reference herein in their entireties.

SUMMARY OF THE EXEMPLARY EMBODIMENTS

In accordance with one exemplary embodiment, a substrate thermalprocessing system is provided. The system has at least one substrateholding module having a housing configured for holding an isolatedenvironment therein. A substrate heater is provided located in thehousing and having a substrate heating surface. A substrate cooler isprovided located in the housing and having a substrate cooling surface.An gas feed opening is provided into the housing and feeding inert orreducing gas into the housing when the substrate is heated by theheating surface. A gas restrictor is provided within the housingrestricting the fed gas between the substrate heating surface and asurrounding atmospheric region substantially surrounding the substrateheating surface in the housing and forming an aperture through which thefed gas communicates with the atmospheric region.

In accordance with another exemplary embodiment, a substrate thermalprocessing system is provided. The system has at least one substrateholding module having a housing configured for holding an isolatedenvironment therein. A substrate heater is provided located in thehousing and having a substrate heating surface. A substrate cooler isprovided located in the housing and having a substrate cooling surface.A gas feed opening is provided into the housing and feeding inert orreducing gas into the housing when the substrate is heated by theheating surface. A gas boundary bounding a first gas region within thehousing from a second gas region within the housing is provided, the gasboundary including the substrate heating surface in the first gasregion, wherein the first gas region contains the fed gas and the secondgas region is substantially atmospheric and wherein the gas boundary hasa boundary opening through which the fed gas passes from the first gasregion to the second gas region.

In accordance with another exemplary embodiment, a system forsemiconductor thermal processing consisting of a plurality of isolatedmodules is provided. Each isolated module has a substrate heater and angas source adapted to provide inert or reducing gas flow duringsubstrate heating. A restriction is provided adapted to restrict gasflow between the substrate heater and the surrounding atmosphericenvironment. A substrate cooler is provided adapted to cool substratesafter heating. A substrate transporter is provided adapted to transportsubstrates from the substrate heater to the substrate cooler.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the exemplary embodimentsare explained in the following description, taken in connection with theaccompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a conventionalvertical-configuration anneal module;

FIG. 2 is a list graphically illustrating a conventional process foroperation of a conventional vertical-configuration anneal module in FIG.1;

FIG. 3 is a top plan view of a conventional horizontal-configurationanneal module;

FIG. 4 is a list graphically illustrating a conventional process foroperation of a conventional horizontal-configuration anneal module inFIG. 3;

FIG. 5 is a side cross-section view of a semiconductor workpiece processmodule incorporating features in accordance with an exemplary embodimentof the invention;

FIG. 6 is a list graphically illustrating an exemplary embodiment of theinvention for operation of the exemplary module shown in FIG. 5;

FIG. 7 is a side cross-section view of another exemplary embodiment of aprocess module;

FIG. 8 is an elevation view of the process module in FIG. 7;

FIG. 9 is a top plan view of the process module in FIG. 8;

FIG. 10 is a perspective view of an exemplary base plate portion of theprocess module in FIG. 8;

FIG. 11 is bottom plan view of an exemplary cooling plate portion of theprocess module in FIG. 8;

FIG. 12 a is a top perspective view of an exemplary heated chuck ofeither exemplary process module illustrated in FIG. 5 or FIG. 7;

FIG. 12 b is a bottom perspective view of the exemplary heated chuck;

FIG. 13 is a side perspective view of an exemplary processing systemincorporating exemplary processing modules similar to the moduleillustrated in FIG. 7; and

FIG. 14 is a list graphically illustrating an exemplary process foroperation of an exemplary process module.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)

Referring now to FIG. 1, there is shown a conventional vertical annealconfiguration 1 containing a semiconductor wafer 5 undergoing an annealprocess. Configuration 1 includes process chamber 2, wafer handler 3,cold plate 4, wafer lift-hoop mechanism 6, heated chuck 8 with embeddedresistive heating coils 7, lift pins 9 a and 9 b, slot valve 10, slotvalve cover 11, vacuum pump 12, vacuum pump valve 13, inert gas source14, and inert gas valve 15. In FIG. 1, the wafer lift-hoop 6 is shown atan intermediate height. Before processing, the hoop would be recessedbelow the heated chuck 7. Also before processing, the chuck 8 would havereached a temperature set-point by heating of the internal resistiveheating coils 7.

Referring now to FIG. 2, there is shown a list graphically illustratinga conventional process when operating vertical anneal configuration 1.The process may include:

201. Select wafer 5 from an internal or external wafer holder (notshown).

202. Transport wafer 5 through the slot valve 10.

203. Place wafer 5 onto wafer lift pins 9 a and 9 b using the internalwafer handler 2.

204. Close gate valve 10 using slot valve cover 11.

205. Evacuate air from the chamber by opening vacuum valve 13.

206. Isolate chamber 2 by closing valve 13.

207. Back-fill chamber 2 with inert gas by opening valve 15.

208. Lower the lift pins 9 a and 9 b to allow thermal contact betweenthe wafer and heated chuck 8.

209. Anneal wafer 5 on heated chuck 8 for a set period of time.

210. Raise wafer 5 using the lift-hoop 6 so that the wafer is in closeproximity to cooling plate 4.

211. Cool wafer 5 by heat exchange with cooling plate 4 for a set periodof time.

212. Extend lift pins 9 a and 9 b.

213. Lower wafer 5 onto lift pins 9 a and 9 b using lift-hoop 6.

214. Open gate valve 11.

215. Transfer wafer 5 to an internal or external wafer holder usingwafer handler 2.

Referring now to FIG. 3 there is shown another conventionalconfiguration 20, here a horizontal anneal configuration, containing asemiconductor wafer 5 undergoing an anneal process. Features inhorizontal configuration 20 which may perform similar functions asfeatures in vertical configuration 1 are labeled with the same numbersto facilitate comparison. These include the cooling plate 4, heatedchuck 8, slot valve 10, vacuum pump 12, vacuum pump valve 13, inert gassource 14, and inert gas valve 15. Other features include externalrobotic end-effector 24 and vertical spacers 22 a, 22 b, and 22 c.Vertical spacers 22 a-c are optionally present in cooling plate 4 aswell as hot chuck 8 of vertical anneal configuration 1.

Referring now to FIG. 4, there is shown a list graphically illustratinga conventional process when operating horizontal anneal configuration20. The process may include:

401. Select wafer 5 from an external wafer holder or processing station(not shown).

402. Transport wafer 5 through a slot valve 10 onto the cooling plate 4using end-effector 24.

403. Retract end-effector 24.

404. Close slot valve 10.

405. Evacuate air from chamber 21 by opening vacuum valve 13.

406. Isolate chamber 21 at low pressure by closing valve 13.

407. Back-fill chamber 21 with inert gas by opening valve 15.

408. Transfer wafer 5 to heated chuck 8.

409. Anneal wafer 5 on heated chuck 8 for a set period of time.

410. Transfer wafer 5 to cooling plate 4.

411. Cool wafer by heat exchange with cooling plate 4 for a set periodof time.

412. Open slot valve 10.

413. Extend end-effector 24 and remove processed wafer 5.

In the embodiments illustrated in FIGS. 1 and 3, the volume of chambers2 and 21 need be sufficiently large to accommodate a variety of featuresincluding wafer handlers 3 and 26 and lift-hoop 6. Since the amount ofgas in supply 14, the size of vacuum pump 12 and the evacuation time allscale with the volumes of chambers 2 and 21, it may be desirable todecrease this volume to a smaller size, preferably the minimum size tocontain wafer 5. It would be further desirable to eliminate vacuum pump12, thus decreasing system cost. Pump and back-fill process actions205-207, 405-407 for configurations 1 and 20 require process time whichreduces system throughput. In some cases, these actions are repeated toachieve a sufficiently low level of residual oxygen. It may be desirableto eliminate these actions in order to improve system throughput.Silicon wafers are fragile and easily broken by mechanical pressure.This is especially true for thin wafers, whose thicknesses range from25-250 um. Thin wafers are increasingly being used for mobileapplications, high-power devices, and in applications usingthrough-silicon-vias (TSV). In the embodiment shown in FIG. 1, whenwafer lift-hoop 6 raises wafer 5 into close proximity with cooling plate4, it is possible that slight mis-adjustment in height could causeexcessive pressure to be applied to the wafer, causing breakage. Even ifthe wafer is not broken, a slight contact of wafer 5 against coolingplate 4 can lead to elevated particle counts at the contact area.Elevated particle counts are associated with reduced device yields andare not tolerated in semiconductor processing. To achieve sufficientcooling rates while preventing wafer breakage or introducing particles,lift-hoop 6 must incorporate precise mechanical controls and interlocks.Further, it may be desirable for an anneal chamber to allow close,adjustable thermal contact between the wafer and a cooling plate,without the need for mechanical positioning. It may be further desirableto allow cooling of thin wafers without mechanical contact. Thin wafersare not as rigid as full thickness wafers, and may be bowed by as muchas several millimeters due to thin-film and fabrication stresses. Abowed wafer placed on heated chuck 8 will not be in good thermal contactwith the chuck over a portion of the wafer surface. As a result, thetemperature profile across the wafer may not be sufficiently uniform. Itmay be desirable for an anneal chamber to easily accommodate processingof thin wafers. Such processing includes the ability to handle thinwafers without breakage as well as ensure a sufficiently uniformtemperature profile. Wafer height spacers 22 a, 22 b and 22 c are usedto support the wafer during heating. They are also used to set the waferheating rate and improve the temperature uniformity. In order to preventparticle generation, it would be desirable to prevent such contact, andcontact the wafer 5 only at the rim or in an area known as the edgeexclusion region. Vertical anneal configuration 1 contains a cold plate4 directly above the heated chuck 8. Horizontal anneal configuration 20contains a cooled metal chamber 21 directly above the heated chuck 8.When hot, chuck 8 will lose heat via convective transport to cooledareas. This is true both when the chuck is bare and when a wafer 5 ispresent on the chuck. At the high temperatures used in annealing,convective heat loss is significantly higher than insulated heat loss.It would be preferable to reduce the heat loss, so as to reduce theheating and cooling costs.

Referring now to FIG. 5, there is shown an exemplary apparatus 40 forthermal processing and post-process cooling of a substrate incorporatingfeatures in accordance with an exemplary embodiment of the presentinvention. The apparatus has a gas micro-environment for substrateheating, cooling and to prevent oxidation while using minimal inert orreducing (or other suitable process) gas flow as will be described ingreater detail below. Embodiments also use gas flow for substratehandling tasks. Although the present invention will be described withreference to the embodiments shown in the drawings, it should beunderstood that the present invention can be embodied in many alternateforms of embodiments. In addition, any suitable size, shape or type ofelements or materials could be used. Although the exemplary thermalprocessing system and method is described for exemplary purposes asapplied to semiconductor annealing, it should be understood that thescope of the disclosed embodiments are not limited to annealing ofsemiconductor substrates, as there are other substrate processingapplications, for example, such as reflow and degas operations, forwhich the disclosed embodiments may also be used.

Referring still to FIG. 5, there is shown a side cross-section view ofthe exemplary semiconductor wafer processing module 40. In theembodiment illustrated in FIG. 5, the processing module is shown forexample purposes as an anneal module having what may be referred to as agenerally vertical configuration (which means that if the module hasboth heating and cooling plates, one is below the other). In alternateembodiments, the process module may be any other suitable type ofthermal process module. In the exemplary embodiment, the anneal module40 comprises a housing defining a chamber 41 containing a Bernoullicooling plate 43 and a heated chuck or plate 42. In alternateembodiments, the module may have either a cooling plate or a heatedplate included in the chamber alone or in combination with other waferprocessing stations. In other alternate embodiments heating and coolingmay be incorporated in a common plate or chuck. As will be furtherdescribed, the chamber 41 may hold a controlled or isolated atmosphereat substantially atmospheric conditions. Inert or reducing (or othersuitable forming or process) gas is fed to Bernoulli cooling plate 43from inert or reducing gas source 14 b through gas inlet 55 when valve115 is open. As noted, gas source 14 b and the gas fed thereby may beinert or reducing gas, and the description hereinafter shall use (forsimplicity) the term “inert” when referring to either inert or reducinggas. Inert gas from inlet 55 enters an internal gas distributionmanifold 44 which directs gas to a nozzle plate 100 containing nozzleholes, including those labeled 45 a and 45 b. Cooling water is suppliedto and from cooling plate by inlet 54 a and cooling water return outlet54 b. Bernoulli cooling plate 43 may contain for example internal watercooling channels, or contain serpentine slots into which copper tubinghas been fitted and adhered using thermally conductive epoxy. Inalternate embodiments, the cooling plate may have any suitable thermaltransfer system for cooling the cooling plate. Cooling plate nozzles,including those shown schematically in FIG. 5 labeled 45 a and 45 b,directs gas at an angle with respect to nozzle plate 100. In theexemplary embodiment, when a wafer 5 is undergoing cooling by coolingplate 43, gas from nozzle plate 100 is used to maintain the wafer 5 at aknown distance with respect to nozzle plate 100 using a process known asBernoulli chucking. The horizontal component of the gas flow directs thesilicon wafer against one or more edge restraints, such as the restraintlabeled 101 a. In the exemplary embodiment, heated chuck or plate 42 maybe surrounded by walls that may be for example thermal insulationincluding insulating base plate 50, radial insulation 49 and moveableinsulating cover 46. Insulating portions 50, 49 and 46 may be fabricatedfrom several layers of stainless steel, and for example may be ofthickness between 0.1-0.5 mm, and for example may be spaced apart by adistance of 0.2-0.7 mm, although other high-temperature-capableinsulating materials such as alumina, quartz or titanium may beemployed. In the exemplary embodiment, heated chuck 42 may containinternal resistive heating coils (not shown) which are fed power byelectrical connection 67 a though in alternate embodiments any suitableheat exchanger may be used to heat the chuck. In the exemplaryembodiment shown a movable cover 46 that may be insulating for example,is attached to cover support 64, which is attached to cover transportassembly 47. A cover transport assembly may move cover 46 from an openposition (not shown) into position over the heating zone, although othergeometries, such as a linear transport method may also be used. Thevolume enclosed by wall portions 50, 49 and 46 may be referred to as theheated zone micro-environment (HZM) 57. The diameter of HZM 57, which inthe exemplary embodiment has a circular configuration, may be, forexample, no more than about 10 mm larger than the diameter of heatedchuck 42, which itself may be, for example, no more than about 25 mmlarger than wafer 5. In alternate embodiments, the heated chuck and HZMmay have any desired dimensions. In the exemplary embodiment, the heightof micro-environment 57, which equals the distance between the top ofheated chuck 42 and the bottom of cover plate 46 may be, for example,less than about 20 mm and more specifically less than about 10 mm. Thegap(s) between walls 49 and movable cover 46 allows inert gas to exitHZM 57 while minimizing the volume of chamber atmosphere that can enterthe micro-environment. The vertical gap height between radial insulation49 and movable insulating cover 46 may be, for example, in the range ofabout 0.05-0.5 mm, and may be, for example, in the range of about0.1-0.2 mm, and the overlap width of the gap length, which equals thewidth of radial insulation 49 may be, for example, greater than about 5mm and may be, for example, greater than about 10 mm. In the exemplaryembodiment, gaps are shown formed at edges between the cover and walls,though in alternate embodiments the cover, walls or both may be porousor ported to allow desired gas flow from HMZ through the cover/walls.Inert gas may be provided by gas source 14 into HZM 57 by inlet tube 64when regulator valve 15 is opened. In the disclosed embodiment, this gasis fed to heated chuck gas inlet 65 which connects to an internal gasmanifold 69 (see FIG. 5)). The gas may then be uniformly distributedinto HZM 57 by a set of nozzle holes, such as those labeled 66 a and 66b shown schematically in FIG. 5. The gas flow set by regulator valve 15may be set sufficiently high so that the mean residence time of gasmolecules in the micro-environment is minimized, for example, less thanabout 10 seconds and by way of further example, less than about onesecond. In the exemplary embodiment, additional means to preventatmospheric oxygen from entering chamber 41 may include nitrogenair-knife 51, slot valve 68, gate valve 52 and exhaust tube 53. Nitrogenair-knife 51 blows nitrogen downward across the chamber entrance whilegate valve 52 is open during wafer exchange. The height of slot valve 68may be, for example, less than about 12 mm and may be, by way of furtherexample, less than about 6 mm and has a horizontal length of at leastabout 5 mm. Exhaust tube 53 has a length that may be for example atleast 10 times its diameter, thereby preventing atmospheric oxygen fromentering chamber 41, as long as a positive inert pressure is maintained.In the exemplary embodiments, the configuration of the cover 46 and wallportions 49 alone or in combination with the interface between heatingsurface and the wafer form what may be referred to as a gas restrictorwithin the housing restricting the inert gas between the substrateheating surface and a surrounding atmospheric region 57′ substantiallysurrounding the substrate heating surface. As seen in FIG. 5, portionsof cover 46 and wall portions 49 and the substrate heating surface inthe housing form an aperture (e.g. via gaps between cover 46 and wallportions 49) through which the inert gas from the HMZ communicates withthe atmospheric region 57′. As may be realized, the cover and wallportions define a gas boundary that bounds a first gas region 57 withinthe housing from a second gas region 57′ within the housing. The gasboundary includes the substrate heating surface in the first gas region,where the first gas region 57 contains the inert gas and the second gasregion 57′ is substantially atmospheric. The gas boundary has a boundaryopening, such as gaps 46, 49, through which the inert gas fed throughthe heating surface when heating a substrate passes from the first gasregion to the second gas region as described.

An exemplary process substrate for operating the anneal module 40 havingthe vertical configuration shown in FIG. 5 is illustrated graphically inFIG. 6. Prior to commencing the process, conditions may be establishedin the chamber 41, such as the oxygen level in chamber 41 may have beenreduced by inert gas flow and heated chuck 42 may have reached aset-point temperature. Valve 15 is open and inert gas flow from source14 remains on through the process.

Referring now to FIG. 6, there is shown a list of process steps whichmay include the following actions and which may be accomplished in anysuitable order:

601. A semiconductor wafer 5 is selected from a cassette or otherexternal wafer holder (not shown) and transported by an end-effector(not shown) under the Bernoulli cooling plate 43.

602. Valve 115 is opened and inert gas flows through the nozzles innozzle plate 100 thereby chucking wafer 5 onto Bernoulli cold plate 43.

603. The end-effector is retracted.

604. The gate-valve 52 is closed.

605. Insulating shield 46 is moved, exposing heated chuck 42.

606. Lift pins 63 a, 63 b are raised to an extended height within a fewmm of wafer 5.

607. Valve 115 is closed, and wafer 5 comes to rest on lift pins 63 aand 63 b.

608. Lift pins 63 a, 63 b are lowered to a middle position, in whichwafer 5 is above the heated chuck 42 but below insulating cover 46.

609. Insulating cover 46 is moved to cover HZM 57.

610. Additional processing is delayed for a recipe-dependentmicro-environment purge time.

611. Lift pins 63 a, 63 b are lowered below the surface of heated chuck42.

612. Wafer 5 is annealed for a recipe-dependent time.

613. Lift pins 63 a, 63 b are raised to a mid-position, in which wafer 5is above the heated chuck 42 but below insulating cover 46.

614. Insulating cover 46 is moved to uncover HZM 57 and wafer 5.

615. Lift pins 63 a, 63 b are raised to an extended position, in whichwafer 5 is within a few mm of Bernoulli cooling plate 43.

616. Open valve 115 in order to chuck wafer 5 onto Bernoulli coolingplate 43.

617. Retract lift pins 63 a, 63 b below insulating cover 46.

618. Move insulating cover 46 over HZM 57.

619. Wafer 5 is cooled for a recipe-dependent time.

620. Nitrogen air-knife 51 is turned on.

621. Gate valve 52 is opened.

622. An end-effector is extended through gate valve 52 under wafer 5.

623. Valve 115 is turned off and wafer 5 comes to rest on theend-effector.

624. The end-effector transports wafer 5 to a cassette or other externalwafer holder for additional processing.

Referring now to FIG. 7, there is shown a cross-section view of anotherexemplary semiconductor wafer processing module 70, incorporatingfeatures in accordance with another exemplary embodiment. In theembodiment illustrated in FIG. 7, the module 70 is shown for examplepurposes as an anneal module having what may be referred to as agenerally horizontal configuration (which means that if the module hasboth heating and cooling plates, one is horizontally offset from theother). In alternate embodiments, the process module may have any othersuitable configuration. Module 70 may comprise a housing similar tohousing 41 shown in FIG. 5, and may be generally similar to module 40described before except as otherwise noted. Module 70 comprises baseassembly plate 73, Bernoulli lift plate 43 a, bridge assembly 72,cooling zone micro-environment (CZM) 57, and heating zonemicro-environment (HZM) 58. Semiconductor wafer 5 is shown in the module70. Features may be machined or formed into the base assembly plate 73to support the CZM include gas nozzles such as those labeled 60 a and 60b and embedded heat-transfer cooling tube 62. As noted before, inalternate embodiments, heat transfer may be effected with any suitableheat exchanger. Inert gas is supplied to nozzles 60 a and 60 b viamanifold 144 when valve 116 is open. Cooling fluid is supplied to andfrom cooling tube 62 via inlet 61 a and exit 61 b. The base assemblyplate 73 also contains features to support thermal insulation 50 andheated chuck or plate 42. In the exemplary embodiment, Bernoulli liftplate 43 a includes a nozzle plate 100 and a plurality of angled nozzlesincluding those labeled 45 a and 45 b as well as cooling tube 63 orother suitable heat exchanger (including active or passive heatexchangers). Inert gas is supplied by gas source 14 to manifold 44 andnozzles including 45 a and 45 b when valve 115 is open. Bernoulli liftplate 43 a is attached to base assembly plate 73, or other portion ofthe module having via suitable actuators (e.g. pneumatic, not shown),which are activated when the CZM gap is opened to accept anend-effector. In the exemplary embodiment, the Bernoulli lift plate 43 aof module 70 has similar functions and features as the Bernoulli coldplate 43 of the module configuration 40 (see FIG. 5), with theadditional capability of actuation, such as vertical motion, toward andaway from base plate 73. The CZM is maintained with the assistance ofinert gas flows from cool-zone base plate nozzles 60 a and 60 b and fromBernoulli lift plate nozzles 45 a and 45 b. When the Bernoulli liftplate is lowered, the height of CZM 59 may be for example between about1-10 mm, and by way of further example between about 1.5-4 mm. The totalinert gas flow through valve 115 and 116 may be, for example, betweenabout 2-60 SLM and may be, by way of further example, between about 5-30SLM. Bridge assembly includes a surface 114 which substantially enclosesthe top of the HZM. HZM top surface 114 contains nozzles including thoselabeled 66 c and 66 d and uses gas flow from these nozzles to creates anupper air-bearing, thereby flattening the wafer. Surface 114 may bethermally insulating surface or it may be the bottom surface of a heatedchuck or plate 42 a substantially similar to heated chuck 42, butmounted so that the wafer interface surface (e.g. heating surface) facesdown or towards the heating plate 42. The HZM 58 is maintained with theassistance of inert gas flows from heated chuck or plate 42 and fromsurface 114. In the exemplary embodiment, the heated plate 42 may besimilar to heated chuck or plate 42 described before and shown in FIG.5. The HZM 58 in the exemplary embodiment is thus bounded by surface 114of plate 42 a and the wafer interface surface of heated chuck 42 asshown. The height of HZM 58 may be, for example, between about 1 andabout 10 mm, and may be by way of further example, between about 1.5-4mm, and the inert gas flow through valve 117 may be, for example,between about 2-60 SLM and may be by way of further example, betweenabout 5-30 SLM. In the exemplary embodiment, the surface 114 of the HZM58 is shown as being substantially fixed, though in alternateembodiments, the surface may be movable towards and away from the heatedcover with suitable actuators. Similar to module 40, describedpreviously, the CZM 57 and HZM 58, alone or in combination with theinterface between the wafer 5 and the interface surfaces that bound theCZM and HZM, form the gas restrictor within the module housing,restricting the inert gas between the wafer interface (e.g. heating,cooling) surface(s) and the surrounding atmospheric region 57′surrounding the wafer interface surface(s). As seen in FIG. 7, the CZM57 (formed between wafer interface surfaces of lift plate 43 a and coldplate that bound the CZM) and the HZM 58 (formed between wafer interfacesurfaces 114 of heated plate 42, 42 a that bound the HZM) form aperturesthrough which the inert gas from the CZM, and/or HZM communicates withthe atmospheric region 57′.

Referring now to FIG. 8, there is shown an elevation view of ahorizontal anneal module 70. Bernoulli lift plate 43 a is raised andlowered by pneumatic actuator assembly 69. The Bernoulli lift plate 43 ais shown in a raised position such as may be used during transfer ofwafer into CZM 57.

Referring now to FIG. 9, there is shown a top plan view of a horizontalanneal module 70. In the exemplary embodiment, Bernoulli lift plate 43 ais attached two pneumatic actuator assemblies 69. The configurationshown is exemplary and in alternate embodiments the lift plate may haveany suitable configuration including any number of one or more actuatorslocated at any suitable location on the plate and module housing. Anoptical sensor 83 is mounted within lift plate 43 a and senses thepresence of a chucked semiconductor wafer. Cooling water is supplied toand from bridge assembly cooling tube 85 via inlet 84 a and exit 84 b.Cooling water may also be supplied to and from the base assembly 73 viainlet 84 a and exit 84 b. Electrical signals including wafer positionsensing, are communicated to the control system via connector 88.

Referring now to FIG. 10, there is shown a top, perspective plan view ofa base assembly 73 illustrating wafer transport features of a horizontalanneal module 70 in accordance with an exemplary embodiment. In theexemplary embodiment, a wafer may be supported during transport, such asbetween CZM 57 and HZM 58, by an air-bearing. The air bearing transportmay be provided by flow from nozzles such as 60 a and 60 b in the CZMand 66 a and 66 b in the HZM. In the exemplary embodiment, fingers 92 aand 92 b may contact the edge of the wafer and guide the wafer betweenthe CZM and the HZM. The fingers 92 a and 92 b may be guided duringmovement, such as by being attached to bearing blocks 97 a and 97 bwhich are attached to linear rails (not shown). The bearing blocks mayalso be attached to drives 96 a and 96 b (for example, by chain drives),which are driven by motor 91 via a suitable transmission (e.g. sprocketgears attached to drive-shaft 90).

Referring now to FIG. 11, there is shown a bottom plan view of aBernoulli lift plate 43 a in accordance with an exemplary embodiment.Inert gas may be fed into inlet 55, and exits from nozzle plate 100 viaangled nozzles including 45 a and 45 b (see also FIG. 7). Gas flowdirects a chucked wafer against end stop sets 101 a and 101 b. The endstop position may be variable and is wafer-size dependent, for exampleend stops 101 a and 101 b are moved to position 102 a and 102 b to chucka smaller wafer. The Bernoulli nozzle plate 100 may be made fromtitanium although stainless steel or any other suitable material mayalso be used. For embodiments using a metal nozzle plate, angled nozzleholes 45 a and 45 b are fabricated using either laser drilling or EDMmachining. The Bernoulli lift plate may also be constructed from aporous graphite media, which acts as a filter to prevent particles inthe gas stream from reaching the wafer. In this case, the nozzles 45 aand 45 b are small pores in the graphite surface and the gas exits theporous surface in a direction perpendicular to the surface. The porousmedia thus creates an air bearing to maintain the wafer at the properdistance from nozzle plate 100, but requires an additional mechanism tomaintain the wafer in the proper horizontal location. This horizontalpositioning is accomplished by several channels in the wafer edgeexclusion region which are provided with vacuum.

Referring now to FIGS. 12 a and 12 b, there are shown respectively topand bottom perspective views of a heated chuck 42 of the disclosedembodiment showing electrical connections 67 a and 67 b, gas inlet 65and gas nozzles 66 a and 66 b. Heated chuck 42 may be aluminum which hasreceived a hard anodization (Type III) coating to prevent particleformation or corrosion.

Referring now to FIG. 13, there is shown a side perspective view of ananneal system 120 incorporating anneal modules of the disclosedembodiments. Anneal system 120 includes rack-mounted heating controlmodule 121, four vertically-stacked horizontal-configuration annealmodules 70 and facilities interface panel 122. Anneal system 120 can beconfigured as a stand-alone system or attached to a electro-plating toolusing interface features incorporated into alignment assembly 123.

An exemplary process suitable for operating the anneal module 70 havingthe horizontal configuration is illustrated graphically in FIG. 14.Prior to commencing the process, conditions may be established in themodule, such as, the oxygen level in HZM 58 has been reduced by inertgas flow and heated chucks 42 and 42 a have reached set-pointtemperature. Valve 117 is open and inert gas flow from an inert gassource 14 remains on through the process.

Referring now to FIG. 14, there is shown a list of process steps whichmay include the following actions (which may be accomplished in anysuitable order):

141. A semiconductor wafer 5 is selected from a cassette or otherexternal wafer holder (not shown) and transported by an end-effector(not shown) under the Bernoulli lift plate 43 a.

142. Valve 115 is opened and inert gas flows through

Bernoulli lift plate nozzles including 45 a and 45 b, thereby chuckingwafer 5 onto Bernoulli lift plate 43 a.

143. The end-effector is retracted.

144. Bernoulli lift plate 43 a is lowered.

145. Valve 115 is closed, placing wafer 5 between transport fingers 92 aand 92 b.

146. The wafer is guided by transport fingers 92 a and 92 b from the CZM57 into the HZM 58.

147. The wafer 5 is annealed for a recipe-dependent time.

148. The wafer 5 is guided by transport fingers 92 a and 92 b from theHZM 58 into the CZM 57.

149. The wafer 5 is cooled for a recipe-dependent time.

1410. Valve 115 is opened and inert gas flows through Bernoulli liftplate nozzles including 45 a and 45 b, thereby chucking wafer 5 ontoBernoulli lift plate 43 a.

1411. Bernoulli lift plate 43 a is raised.

1412. An end-effector is moved under the Bernoulli lift plate 43 a.

1413. Valve 115 is closed, placing wafer 5 onto the end-effector.

1414. The end-effector is withdrawn and the wafer is placed into acassette or other external wafer holder (not shown).

The disclosed embodiments provide an apparatus for thermal processingand cooling of semiconductor wafers. The apparatus incorporates a heatedzone micro-environment (HZM). The HZM is a minimal-volume processingenvironment which prevents wafer oxidation using a continuous minimumquantity of inert gas flow. The apparatus is constructed with anatmospheric, rather than a vacuum-compatible chamber, as the HZM doesnot require evacuation and gas back-filling in order to achieve asufficiently low oxygen concentration in a minimal time. Further, theapparatus may not include expensive vacuum pump components. Someembodiments may incorporate an air-bearing cooling plate to maintain theproximity of a substrate to the cooling plate without touching theplate. Other embodiments incorporate a combination Bernoulli andair-bearing plate to position the wafer against retaining fixtures at afixed distance to the cooling plate, without touching the plate. Theair-bearing cooling plate includes inlet means for introducing inertgas, a manifold for distributing the inert gas and a nozzle plate forproducing the air bearing. Additionally, the cooling plate includesinlet means for introducing cooling fluid, internal channels to allowthermal heat transfer, and exit means for removing the cooling fluid.Nozzle plates for embodiments incorporating Bernoulli air-bearing platesinclude angled nozzle-hole patterns to direct a semiconductor waferagainst a retaining feature. The air-bearing cooling plate mayincorporate a porous media air bearing to provide a uniform air bearingwith minimal particle generation. The apparatus may include one or moreair bearing heated chucks to maintain the wafer at a fixed distance withrespect to the chuck. Further, the heated chuck air bearing providesuniform heating while preventing contact between the wafer and thechuck, thus preventing particle generation. The heated air bearing chuckincludes inlet means for introducing inert gas, a manifold fordistributing the inert gas and a nozzle plate for producing the airbearing. The heated air bear chuck additionally includes a resistiveheater designed in a serpentine pattern, the design of which isoptimized to provide uniform surface heating while accommodating theinternal inert gas manifold. Some embodiments incorporate both a heatedzone microenvironment (HZM) and a cooled zone microenvironment (CZM).These embodiments create the HZM and CZM using a narrow gap to restrictinert gas flow. They may also include air bearing transport means whichenable wafer movement between the CZM and HZM. The transport meansincludes fingers which contact the wafer only in the rim edge exclusionarea. The air bearing transport means include a single motion axis, thusreducing cost and complexity. Some embodiments utilize two sets of airbearings, one above the wafer and one below the wafer. Such embodimentshave the capacity to flatten and process bowed wafers, and to preventcontact of the wafer with the surfaces which surround themicro-environments.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

1. A substrate thermal processing system comprising: at least onesubstrate holding module having a housing configured for holding anisolated environment therein; a substrate heater located in the housingand having a substrate heating surface; a substrate cooler located inthe housing and having a substrate cooling surface; an gas feed openinginto the housing and feeding inert or reducing gas into the housing whenthe substrate is heated by the heating surface; and a gas restrictorwithin the housing restricting the fed gas between the substrate heatingsurface and a surrounding atmospheric region substantially surroundingthe substrate heating surface in the housing and forming an aperturethrough which the fed gas communicates with the atmospheric region. 2.The system of claim 1, wherein the substrate cooler is located in aposition above the substrate heater.
 3. The system of claim 1, whereinthe substrate cooler is located in a position substantially horizontallyadjacent to the substrate heater.
 4. The system of claim 1, wherein thesubstrate heater comprises one or more heated plates, each having atleast one resistive heating element positioned in an interior portion ofthe plate and a plurality of gas nozzles directed toward a substratereceiving surface.
 5. The system of claim 1, wherein the substratecooler comprises a cooled plate in fluid communication with a coolingfluid and a plurality of gas nozzles directed toward a substratereceiving surface.
 6. The system of claim 1 further comprising asubstrate transporter having air bearings between the substrate heaterand the substrate, and between the substrate cooler and the substrate.7. The system of claim 1, wherein the fed gas flow is between about 2and about 60 SLM.
 8. A substrate thermal processing system comprising:at least one substrate holding module having a housing configured forholding an isolated environment therein; a substrate heater located inthe housing and having a substrate heating surface; a substrate coolerlocated in the housing and having a substrate cooling surface; an gasfeed opening into the housing and feeding inert or reducing gas into thehousing when the substrate is heated by the heating surface; and a gasboundary bounding a first gas region within the housing from a secondgas region within the housing, the gas boundary including the substrateheating surface in the first gas region, wherein the first gas regioncontains the fed gas and the second gas region is substantiallyatmospheric and wherein the gas boundary has a boundary opening throughwhich the fed gas passes from the first gas region to the second gasregion.
 9. The system of claim 8, wherein the substrate cooler islocated in a position above the substrate heater.
 10. The system ofclaim 8, wherein the substrate cooler is located in a positionsubstantially horizontally adjacent to the substrate heater.
 11. Thesystem of claim 8, wherein the substrate heater comprises one or moreheated plates, each having at least one resistive heating elementpositioned in an interior portion of the plate and a plurality of gasnozzles directed toward a substrate receiving surface.
 12. The system ofclaim 8, wherein the substrate cooler comprises a cooled plate in fluidcommunication with a cooling fluid and a plurality of gas nozzlesdirected toward a substrate receiving surface.
 13. The system of claim 8further comprising a substrate transporter having air bearings betweenthe substrate heater and the substrate, and between the substrate coolerand the substrate.
 14. The system of claim 8, wherein the fed gas flowis between about 2 and about 60 SLM.
 15. A system for semiconductorthermal processing having a plurality of isolated modules, each of theplurality of isolated module comprising: means for heating of asubstrate, the means for heating being surrounded by an atmosphericenvironment inside the isolated module; a gas source adapted to provideinert or reducing gas flow during substrate heating of the substratewith the means for heating; means for restricting gas flow between themeans for heating the substrate and the surrounding atmosphericenvironment; means for cooling substrates after heating; and a substratetransporter adapted to transport substrates from the substrate heater tothe substrate cooler.
 16. The system of claim 15, wherein the means forcooling is located in a position above the means for heating.
 17. Thesystem of claim 15, wherein the means for cooling is located in aposition substantially horizontally adjacent to the means for heating.18. The system of claim 15, wherein the means for heating comprises oneor more heated plates, each having at least one resistive heatingelement positioned in an interior portion of the plate and a pluralityof gas nozzles directed toward a substrate receiving surface.
 19. Thesystem of claim 15, wherein the means for cooling comprises a cooledplate in fluid communication with a cooling fluid and a plurality of gasnozzles directed toward a substrate receiving surface.
 20. The system ofclaim 19, wherein the cooled plate is made of metal.
 21. The system ofclaim 19, wherein the cooled plate is made of a solid porous media. 22.The system of claim 15, wherein the inert gas comprises nitrogen. 23.The system of claim 15, wherein the reducing gas comprises a combinationof nitrogen and hydrogen.
 24. The system of claim 15, wherein the fedgas has a residence time less than about 10 seconds.
 25. The system ofclaim 15, wherein the fed gas has a residence time less than about 1second.
 26. The system of claim 15, wherein the means for restrictingcomprises a cover which moves by rotation or translation and whichencloses the means for heating during anneal processing.
 27. The systemof claim 26, in which the vertical gap between the moveable cover andthe containment for the means for heating is between about 0.05 andabout 0.5 mm and the overlap of the moveable cover over the containmentfor the means for heating is greater than 5 mm.
 28. The system of claim15, where in the substrate transporter comprises a plurality of liftpins.
 29. The system of claim 15, wherein the means for restrictingincludes a nitrogen air-knife.
 30. The system of claim 15, wherein themeans for restricting includes a large-aspect-ratio pipe.
 31. The systemof claim 15, wherein the means for restricting comprises a narrowchannel between the heating means and the atmosphere.
 32. The system ofclaim 31, wherein the narrow channel has a height between about 1.5 andabout 10 mm.
 33. The system of claim 15, wherein the fed gas flow isbetween about 2 and about 60 SLM.
 34. The system of claim 15, whereinthe fed gas flow is between about 5 and about 30 SLM.
 35. The annealingsystem of claim 15, wherein the substrate transporter comprises airbearings between the substrate heater and the substrate, and between thesubstrate cooler and the substrate.
 36. The annealing system of claim15, wherein the substrate is guided over air bearings by guide fingerswhich contact the substrate only at the substrate edge.